| --- |
| id: streamedQuery |
| title: streamedQuery |
| --- |
| |
| `streamedQuery` is a helper function to create a query function that streams data from an [AsyncIterable](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/AsyncIterator). Data will be an Array of all the chunks received. The query will be in a `pending` state until the first chunk of data is received, but will go to `success` after that. The query will stay in fetchStatus `fetching` until the stream ends. |
|
|
| To see `streamedQuery` in action, take a look at our chat example in the [examples/react/chat directory on GitHub](https://github.com/TanStack/query/tree/main/examples/react/chat). |
|
|
| ```tsx |
| import { experimental_streamedQuery as streamedQuery } from '@tanstack/react-query' |
| |
| const query = queryOptions({ |
| queryKey: ['data'], |
| queryFn: streamedQuery({ |
| queryFn: fetchDataInChunks, |
| }), |
| }) |
| ``` |
|
|
| > Note: `streamedQuery` is currently marked as `experimental` because we want to gather feedback from the community. If you've tried out the API and have feedback for us, please provide it in this [GitHub discussion](https://github.com/TanStack/query/discussions/9065). |
|
|
| **Options** |
|
|
| - `queryFn: (context: QueryFunctionContext) => Promise<AsyncIterable<TData>>` |
| - **Required** |
| - The function that returns a Promise of an AsyncIterable of data to stream in. |
| - Receives a [QueryFunctionContext](../../framework/react/guides/query-functions.md#queryfunctioncontext) |
| - `refetchMode?: 'append' | 'reset' | 'replace` |
| - Optional |
| - Defines how refetches are handled. |
| - Defaults to `'reset'` |
| - When set to `'reset'`, the query will erase all data and go back into `pending` state. |
| - When set to `'append'`, data will be appended to existing data. |
| - When set to `'replace'`, all data will be written to the cache once the stream ends. |
| - `maxChunks?: number` |
| - Optional |
| - The maximum number of chunks to keep in the cache. |
| - Defaults to `undefined`, meaning all chunks will be kept. |
| - If `undefined` or `0`, the number of chunks is unlimited. |
| - If the number of chunks exceeds this number, the oldest chunk will be removed. |
|
|
